Backup power system for Aircurve 10 ASV and oxygen concentrator

[KallyA]

Thank you so much for your responses. It looks like powering the oxygen concentrator is the biggest problem. If I used oxygen cylinders in an emergency, I could get by just powering the ASV with humidifier. I read lithium batteries cost more up front, but last longer, take less maintenance and avoid the outgassing problems of lead acid batteries. What would be a good lithium solution just for the ASV?

[Gideon]

What is the distribution (length) of the power outages you want to protect against?

[KallyA]

One night would be excellent

[OMyMyOHellYes]

First thing you need to do is get the ResMed Battery guide.

https://www.resmed.com/us/dam/documents/...lo_eng.pdf

It will help you understand what the current draw is for your unit (or one like it) at given pressures and humogrificator settings. It will tell you what size (amp hour) battery you would need for a night's service in your configuration. Their ratings are sized at 150% of actual requirements as condition of battery varies over time so this is a safety factor.

And the comment as to lithium ion batteries being safer, whoa. that could not be further form the truth, in general... in my opinion.

Sealed lead acid is what most are talking about, generally not wet batteries. There's a reason you can't take Lithium Ion batteries in your checked baggage on commercial flights. And why lithium batteries have safety bags for charging. No, not all of them, but they do have some nasty habits (really expensive Lithum Iron Phosphate chemistry batteries not nearly so much so - and they are far lighter than lead batts, but ungodly expensive).

Most cost effective (economically) and probably easiest is a sealed lead acid - SLA - (I find a 35-39 amp hour battery will last me about 8 nights with no humogrificated air. Probably 3 night if I was silly enough to leave on humogrification in a battery use situation. And at around 25 pounds, the 35-39 AH batteries are still easy ehough to pretty easily move around the house). No worries about spills or gassing with the SLA batteries in almost all instances.

As you have a ResMed unit, the evil marketing and engineering folks got together and decided you will still need one of their DC-DC converters, even if you use a 24 V battery...

A decent smart charger for the SLA is a good investment (I am gravitating towards the NOCO chargers lately, also a user of Deltran Batter Tender chargers.

[RayBee]

Hi Kally.

I found some great information for you. ResMed's Power Consumption Guide shows the AirCurve 10 ASV plus Humidifier consumes 27 Wh of power.
https://sleepright.com.au/wp-content/upl...mption.pdf

27 Wh x 8 hours = 216 Wh power consumption for the night including the humidifier. All things considered, not bad. However without the humidifier, power consumption drops to only 9 Wh. You can also find many Power Meters on Amazon for $15 to 30 - search "Power Meter". With that device, you can plug in your ResMed AirCurve 10 ASV and run it how you normally do over a typical night and get some real numbers for your device's settings. The Power Meter will read out in KWh (K = Kilo) used, so just divide by 1,000 to get Wh for your calculations.

Lithium batteries have an defined relationship of depth of discharge vs number of recharge cycles. In my Radio Control helicopters, I fly Li-Ion (Lithium Ion) batteries, and it is common practice to not discharge them any deeper than 65%. This maximizes the number of recharges or flights we can take on any given battery pack. So we leave 35% "in the tank" rather than discharge them fully. This may be somewhat ignored in your situation because you are using Lithium batteries differently than me. And the backup devices commercially available should have some amount of protection built in - "should". You will only be discharging them occasionally in theory. I discharge my repeatedly and of course, don't want to crash an expensive model helicopter.

Next you can shop for a battery backup device. Search Amazon for "Portable Power Station" (more of a camping style device) or "Pure Sine Wave UPS" (computer backup power supply style device). Just make sure the Wh rating at least hits your minimum, and it has a Pure Sine Wave Output, and it has Lithium batteries. Other than that, read the reviews and look for a product highly rated and supported.

Some common capacities I found under "Portable Power Stations" include: 240 Wh; 300 Wh; 350 Wh.
216 Wh / 240Wh = 90% used in 8 hours or 10% left in the tank.
216 Wh / 300 Wh = 72% used or 28% left in the tank.
216 Wh / 350 Wh = 62% used or 38% left in the tank.

All things considered, you could triple your usage by turning off the humidifier. And/or use it for other things, like LED lighting if you know power will be restored before you need it for your ResMed machine.

You may want to read an interesting post on the Apnea Board by AndyB titled "Resmed Converter with Jackery Explorer 160 Battery" on this topic.
http://www.apneaboard.com/forums/Thread-...+sine+wave
I hope this helps.   

RayBee

[OMyMyOHellYes]

"Pure sine wave" is pure bovine flatulence. At least as far as using inverter output for CPAP machines, which must then go through a DC converter which makes nice clean DC output that the CPAP uses.

And inverters are a really terrible idea anyway... At least when running off a battery. WAY too inefficient. Take 12 V DC and burn some of it's power to make it 120V AC and then run that thorugh a DC converter to turn it right back in to 12 V DC.....

Computer UPS units are a really bad idea if you hope to run through the night. They simply don't have the reserve to power most units all night long... And at the end of the day, they are just a battery and charger hooked up to an inverter with some switches in there.

And using watt-hours is a really unnecessary complication. The ResMed battery guide (see link in my post above) offers information in amp hours. The single page tear sheet (Power Consumption Guide) does not offer the granularity to really tell what your machine does... Vast over simplification to the point where it really is not meaningful (tried to give WH values at a RANGE of pressures -which is not good - need average current draw at different pressures and humidification settings if using humidification. When I calculated battery size/requirements for my backup system, I used a couple different professional grade multimeters (Fluke and Keysight/Hewlett-Packard) over many multiple days to map current draw at various average pressure settings and found that even the ResMed battery guide overstated current draw by a big margin but that's OK because your machine will likely run longer than they are estimating. If you use their estimates, you should be safe in getting their calculated battery yield..) Amperage measures the current draw of the motor as it is in use. If you are taking watt hours, you are having to measure amps and then multiply everything by 12 or 24. Most deep cycle kind of batteries are rated in amp hours.

[RayBee]

And the comment as to lithium ion batteries being safer, whoa.  that could not be further form the truth, in general...  in my opinion.

OMyMyOHellYes has a point. Well, yes, and no.
Yes, when they let loose and burn up, they are quite intense and devastating.   But in almost all cases it is due to abuse of the offending battery - improper charging on a non-Li-Ion charger being the biggest offender, and induced by the novice user of individual cells. (This one problem gave them a bad rap early on) Also, pinholes in the plastic seal exposing the Lithium to oxygen - pretty rare for a manufacturing defect such as this but physical abuse can produce a pinhole. Spontaneous combustion, well, dare I say never (barring abuse). Don't know the stats, but I'm sure it's one in millions, if that, and likely a rare manufacturing defect.

No, there are millions of Li-Ion batteries entrusted to occupy close quarters with the family jewels on a regular basis in the form cell phones and laptop computers. You see a one-off case on TV in how many years time?  Not talking about the obvious cases of manufacturer's design flaws going into mass production - like the hoverboard fame, uh, or flame as the case may be.    Don't want to name the cell phone manufacturer, but we all know that was a design flaw too, that unfortunately went into mass production.

As long as the intelligent charger is built into the device, there isn't much to be worried about. I suppose if you have a dislike for Li-Ion batteries, you can always choose to leave your cell phone and laptop in the flame-proof bag inside the Webber BBQ in the back yard before you step inside the house.
Lithium based batteries seem to be in almost everything these days. Technology has come a long way since they were first introduced into the marketplace and wholly misunderstood. But can you now say Tesla or Prius?

As OMyMyOHellYes says though, sealed Lead Acid batteries are a great alternative and are also widely used and relatively cheap. Don't count them out when shopping for a battery backup solution.  

RayBee

[KallyA]

Thank you so much for your replies.
Which type of battery is safer around oxygen?

[RayBee]

Thank you so much for your replies.
Which type of battery is safer around oxygen?

Great question. But that I don't know. My guess is the answer would be "medical grade" equipment or not. And on Amazon, that would most likely be "not".

Also, I would think the question of "safe around oxygen" might be better if applied to the entire battery backup system you may be considering rather than just the battery type. You may be able to ask the question of the manufacturer's of backup equipment. Or perhaps others on the Apnea Board might be able to provide good input.

A simple solution might be in using an extension cord with any of the backup offerings. You may just consider putting the backup system in another room or closet as long as its has adequate ventilation to prevent overheating. The device may also have a cooling fan that you might not want to hear at night either. So an extension cord may be a great solution.

It would be nice to share your experience and success with whatever battery backup system you choose, so that others may consider doing the same.

All the best.

RayBee

[OMyMyOHellYes]

I'm curious.

If using an O2 concentrator, the O2 saturation in the room is gonna remain around 20 ish percent and around 80 ish percent nitrogen. All that does is separate the two. That won't change the mixture in the room, just at the machine up to the nasal booger prong thingie...

On bottles, I still don't see ambient air in the room going much richer.

So, is there really an issue unless you're making sparks right under the nose? And most batteries are not gonna make sparks unless you short the terminals. And that can be pretty easily prevented with a box, terminal cover or electrical tape.